Acne Vulgaris: Do You Know Your Comedones?

Quick facts!

Acne vulgaris is a chronic inflammatory dermatosis, notable for open or closed comedones and inflammatory lesions, including papules, pustules, or nodules. It is a clinical diagnosis. 

Check out evidence-based management in the 2016 AAD guidelines

Choosing Wisely recommends against routine microbiologic testing in the evaluation and management of acne. 

Think about pathophysiology before you treat!

First, a few key terms: 

  • Pilosebaceous unit = hair follicle and attached sebaceous gland
  • Infundibilum = part of follicle above the sebaceous gland
  • Corneocyte = keratinized cells of stratum corneum (upper epidermis)


  1. Follicular plugging
    • Corneocytes become cohesive and increase keratin production
    • Corneocytes accumulate and form plug in upper infundibulum
  2. Increased Sebum Production
    • Stimulated by androgens
    • Keratin and sebum accumulate to form a densely packed plug called a
  3. Acnes Proliferation
    • Acnes live in the keratin/sebum comedone and proliferate
    • Initiates immune response leading to pustule
  4. Inflammation
    • With tight plug and influx of inflammatory cells, pressure builds
    • Comedone wall ruptures under high pressure, leading to spill of bacteria/keratin, and marked inflammatory response 
    • Immune response creates cyst/nodule

Topical therapy

Benzoyl Peroxide:

  • Antibacterial and mildly comedolytic
  • Derm Rec: use 4% on face and 10% on body

Topical Antibiotics: Clindamycin 1%

  • Should NEVER be used alone due to antimicrobial resistance
  • Erythromycin has fallen out of favor due to resistance

Topical Retinoids: tretinoin, adapalene, tazarotene

  • Binds to different retinoic acid receptors
  • Comedolytic and anti-inflammatory
  • Side effects: drying, peeling, redness (all dose dependent)

Combination therapies exist!

Note: Poor evidence for salicylic acid

Example Prescription for Topical Therapy


  • Benzoyl Peroxide: 4% on face, 10% on body
  • Once patted dry, use clindamycin 1% lotion


  • Wash with face wash
  • When dry, apply pea size amount of tretinoin (start 2 nights per week and

Systemic Antibiotics

Tetracycline class → doxycycline or minocycline

  • Antibacterial and anti-inflammatory
  • Goal to use for as short duration as possible. Re-evaluate in 3-4 months
  • Always combine with topical therapy
  • Dosing: doxycycline effective at 1.7-2.4 mg/kg
    • Also can be used at subantimicrobial dosing at 40mg daily (or 20mg BID) in moderate inflammatory acne

Hormonal Agents

OCPs (women)

  • Anti-androgenic → decreased production at level of ovary and increased sex hormone binding globulin (binding free testosterone)
  • Usual contraindications apply

Spironolactone (women)

  • Anti-androgenic → decreases testosterone production and competitively inhibits binding of testosterone to receptors in skin
  • Improvement in acne seen at 50-200 mg
  • Japanese trial: 200 mg for 8 weeks, followed by 50 mg taper every 4 weeks
  • Only check potassium if on concomitant med
  • Not FDA approved


  • Indication: moderate/severe acne that is resistant to other treatments, produces physical scarring, or causes psychosocial distress
  • Conventional Dosing: 0.5 mg/kg/day for first month. Increase to 1 mg/kg/day as tolerated.
  • Low dose (0.25-0.4 mg/kg/day) reasonable for moderate acne
  • Cumulative dose goal: 120-150 mg/kg
  • Side effects: dose dependent, mimic hypervitaminosis A
  • Lab monitoring: lipid panel and hepatic function panel (specifically looking at triglycerides, cholesterol, and transaminases)
  • iPledge → Contraception (29% don’t comply)


Unfortunately there is no universal grading or classification system for acne, although definitions have been proposed.


  • Scattered, few comedonal or inflammatory lesions; <20 comedones or <15 inflammatory lesions or < 30 lesions total


  • Greater number of sites or lesions than mild acne
  • 20-100 comedones or 15-50 inflammatory lesions or 30–125 lesions total


  • Numerous large papules and/or pustules; multiple nodules and deep lesions; associated anxiety or depression secondary to acne; or scarring

Blog post based on Med-Peds Forum talk by Sam Masur, PGY3

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